Recent evidence indicates that the prevalence of substance abuse is significant among children and adolescents, and initiation of drug use is often occurring at very early ages. These findings underscore the need to initiate age-appropriate prevention efforts with youth at an early age in elementary school and continue these interventions throughout middle school and later years. We previously developed and evaluated an interactive, computer-based drug abuse prevention multimedia program for middle school-aged youth that incorporates effective components of both drug abuse prevention science and educational technologies (called Head On: Substance Abuse Prevention for Grades 6-8 TM). This computer-based program was designed to promote the increased adoption of effective prevention science, and was shown to be easily exportable, able to be applied with fidelity, cost-effective and efficacious in increasing accurate knowledge about substance abuse prevention and decreasing rates of cigarette and alcohol use, intentions to use substances and positive attitudes toward substances among middle school-aged youth. In Phase I of this STTR project, we developed and demonstrated the scientific, technical and commercial merit and feasibility of a prototype of a computer-based drug abuse prevention program for elementary school-aged children (called Head On: Substance Abuse Prevention for Grades 3-5 TM). In this Phase II application, we propose to complete the development and conduct a controlled school-based evaluation of the effectiveness of the computer-based prevention program in increasing knowledge about substance abuse prevention, retarding initiation of substance use and increasing a wide variety of protective factors against substance abuse in elementary school-aged children. This program may extend effective prevention science to this age group, while addressing many of the challenges associated with the current delivery of evidence-based prevention programs. An effective, multimedia substance abuse prevention learning environment, which provides an integration between state-of-the-art computer technology and prevention science research, may be of substantial benefit in providing drug abuse prevention education to elementary school children. This program may deliver evidence-based substance abuse prevention in a manner that is considerably more cost-effective than the labor-intensive, prevention interventions that have been demonstrated to be efficacious in preventing the initiation of drug use among this age group.